Deltares trends & responses of 8 deltas


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Deltares trends & responses of 8 deltas

  1. 1. Towards sustainable development of deltas, estuaries and coastal zones Trends and responses
  2. 2. Towards sustainable development of deltas, estuaries and coastal zones Trends and responses January 21, 2009
  3. 3. Contents Preface 5 1. Trends and issues in the development of deltas 7 1.1 Deltas: economic and environmental hot spots 7 3 1.2 Deltas: melting-pot of drivers and trends 9 1.3 Issues at stake in deltas 11 1.4 Conceptual view on planning of delta development 18 1.5 A closer look at some societal trends 19 1.6 Linking responses to drivers and trends 21 2. Management and restoration of natural systems 23 2.1 Functions and values of deltas 23 2.2 Natural coastal protection and wetland restoration 31 2.3 Integrity of ecosystems: biodiversity, environmental flows 33 2.4 Room for rivers 37 2.5 Multiple use of wetlands 39 3. Extension and revitalization of infrastructure 41 3.1 Role of infrastructure in delta development 41 3.2 Infrastructure to support economic development 43 3.3 Rehabilitation of infrastructure 48 3.4 New approaches in design of infrastructure 50
  4. 4. 4. Development and adaptation of land and water use 57 4.1 Modes in adaptation of land and water use 57 4.2 Spatial planning and zoning 58 4.3 Urban (re)development 60 4.4 Adaptation to flood risks 62 4.5 New agricultural practices to adapt to salinity problems 63 4.6 Adaptation to climate change 64 5. Governance of delta development and management 69 5.1 Role of governance in delta development 69 5.2 Co-operation between levels and sectors of government 71 5.3 Cooperation between government and private sector 77 5.4 Involvement of stakeholders and citizens 80 5.5 Approaches for dealing with risks and uncertainties 83 4 6. Way forward? 87 6.1 Two conflicting perspectives on development of deltas 87 6.2 Enabling the sustainable development of deltas 90 6.3 Delta vision: a shared view on delta development 91 6.4 Delta technology: innovations in science and technology 92 6.5 Delta governance: social and institutional innovations 93 6.6 Delta dialogue: establishing best delta practices 94 References 97
  5. 5. Preface This research on deltas, estuaries and coastal zones is part of the preparation of the Aquaterra 2009 Conference and the World Forum on Delta and Coastal Development. Deltas may be defined as low-lying areas where a river flows into a sea or lake. A delta is often considered a different type of river mouth than an estuary, although the processes shaping deltas and estuaries are basically the same. In line with the scope of the Aquaterra Conference we have adopted in this research a broad interpretation of deltas which includes deltas proper, estuaries and the adjacent coastal zone. Deltas are areas with major economic potential as well as large environmental values. The challenge for sustainable development of deltas is to strike a balance between economic development and environmental stewardship. The Aquaterra Conference will present and discuss the state and future of deltas worldwide, with a special focus on eight selected deltas. All these selected deltas are densely populated and/or economically developed. 5 • Yellow River Delta (China) • Mekong River Delta (Vietnam) • Ganges–Brahmaputra Delta (Bangladesh) • Ciliwung River Delta (Indonesia) • Nile River Delta (Egypt) • Rhine River Delta (The Netherlands) • Mississippi River Delta (USA) • California Bay Delta (USA) Another focus of the Aquaterra Conference is the response in deltas to a number of drivers such as economic growth and climate change as well as to a number of trends in society such as privatization and decentralization. Four response themes are being considered: • Natural systems (management and restoration) • Infrastructure (extension and revitalization) • Land and water use (development and adaptation) • Governance (of delta development) The research has explored the perspectives of and experiences with these response themes. Some of these responses may already be classified as ‘best
  6. 6. practices’ or better ‘good ideas’ (at least in the local context), others are yet promising approaches. Anyway, the research aims to provide an overview of current practices in dealing with delta issues. An effort has been made to arrange these practices into global trends. Trends which are illustrated with examples taken from deltas all over the world, with an emphasis on the eight selected deltas of the Aquaterra Conference and in particular the Rhine River Delta. The examples presented are not necessarily the best illustrations of the trends. Own experiences of the researchers as well as easy access to information have played a role in the selection of examples. However, taken together, the trends and examples provide a comprehensive overview of the type of current activities and developments to enable delta life. The focus of the research has been on the identification of issues, trends and responses. The outcome is still qualitative and descriptive. It may be viewed as a first step in the description and analysis of state and future of deltas 6 worldwide. It may be worthwhile to elaborate on the current research. Such elaboration may include a more rigorous assessment of the functioning of deltas based on a set of indicators. Also an extension to other deltas should be included. This might be a nice challenge for future Aquaterra Conferences. Delft, January 2009 Prof. dr. Huib de Vriend, Director Science, Deltares
  7. 7. 1. Trends and issues in the development of deltas 1.1 Deltas: economic and environmental hot spots The major rivers systems of the world all have a unique delta region, with their specific challenges and opportunities. But there are also common characteristics. Deltas are usually areas with major economic potential because of their strategic location close to seas and inland waterways. Deltas provide also some of the world’s most fertile lands important for food production. That is why navigation and port development, oil production and refinery as well as agriculture and fisheries have always been the engines of economic development of deltas. Attracted by these potentials, large numbers of people live in deltas; a development which has led to the growth of coastal (mega-)cities. Population growth and economic development make extensive demands on the available natural resources and trigger pollution. If not properly managed deltas may easily turn into sinks in the frontier between continents and oceans.
  8. 8. Trends and issues in the development of deltas The rivers that flow through the deltas are an important source of fresh water and nutrients that are critical for sustaining life in the deltas. The mixing of salt and fresh water in the estuarine part of the deltas creates environmental conditions for a unique flora and fauna. Delta and estuarine ecosystems are therefore valuable and among the most productive ecosystems on earth. But, being low-lying areas, deltas are also vulnerable to flooding and have to cope with stagnating drainage. That is why living in deltas has always required human intervention. Land reclamation, irrigation, soil drainage and embankments have made many a delta a safe place to live and work. Box 1.1 Opportunities of deltas Challenges in deltas • strategic location close to seas and water ways • areas vulnerable to flooding and drought • high potential for port development and oil • human intervention needed to safely live and industry work • fertile soils and rich aquatic environment • filter or sink for upstream pollution • large potential for agriculture and fisheries • areas with high pressure on available space • valuable and most productive ecosystems
  9. 9. 1.2 Deltas: melting-pot of drivers and trends Population growth, economic development and climate change are the main drivers for change in deltas. These developments pose extensive demands on the available natural resources of deltas. In addition to these drivers there are a number of societal trends which affect the organization and outcome of planning of delta development. The main drivers and trends are briefly described in Box 1.2. Of these trends decentralization and privatization may be viewed as autonomous developments. The challenge is to utilize the advantages of both trends, while minimizing their undeniable drawbacks. This calls for a selective enhancement of governance structures, reflecting the regional scale, integrated nature and long term perspective of delta development. Nile delta
  10. 10. Trends and issues in the development of deltas Box 1.2 Drivers for change Trends in society population growth: the global population still decentralization: brings delta issues closer to grows with some 2% per year, although there are the stakeholders involved. Due to lack of national distinct regional differences. The number of people coordination there is, however, a sincere risk of to be served and to be protected against natural uncontrolled and/or chaotic developments. hazards will increase. economic development: despite the current privatization: public-private partnerships economic recession, economic growth may be are becoming the modus operandi for new expected over larger periods of time, resulting infrastructural projects and services. Increased in larger demands to be met, higher values to efficiency of tax payer’s money is a key motive. protect, more energy to be generated and more The risk of privatization, however, is a focus on goods to be transported. the short term as well as a neglect of the public 10 interest. climate change: although the extent of climate participation: involvement of stakeholders and change may be subject of debate, there is general citizens is important to promote societal support consensus that rise of global temperature is of development projects as well as maintenance of inevitable, with its associated (local) impacts on infrastructure; planning may benefit from the tacit sea level rise and the hydrological cycle (larger and knowledge of stakeholders more frequent droughts and floods) technological development: innovations may environmental concerns: worldwide concern open opportunities to enhance the functionality over a changing climate and environmental of infrastructural solutions, to extend the life time degradation has raised the environmental of infrastructure and/or to develop more cost- awareness; it influences the valuation of impacts effective designs and the choice of measures risk aversion: acceptance of risk is decreasing in our modern societies; hence considerable efforts are made to further reduce or control the risks of natural hazards
  11. 11. 1.3 Issues at stake in deltas Overview of pressing delta issues The characteristics, which make deltas attractive areas to live and work, are under stress. Available space is under pressure, vulnerability to flooding is increasing, fresh water resources are threatened, etc. Population growth, economic development and climate change will cause additional stress on deltas, unless appropriate measures are taken. The main issues at stake in deltas are briefly described in Box 1.3 Box 1.3 Main issues at stake in deltas Pressure on available space: being a focal point of economic development population density is generally high and further rising. Coastal mega-cities have developed; their size and number are growing. 11 Vulnerability to flooding and drought: being low-lying areas, deltas are vulnerable to flooding. Subsidence of soft soils adds to this vulnerability. Accumulation of people and wealth will further increase the vulnerability with respect to climate change. Shortages of freshwater resources: many deltas in the world currently face water shortages. Climate change may result in more frequent and prolonged periods of low river discharges. This will have profound repercussions on the delta agriculture, as well as on delta and coastal ecosystems. Ageing or inadequacy of infrastructure: many deltas have irrigation and drainage systems which require an upgrade or major revision to improve their effectiveness. Other deltas have inadequate flood protection schemes or schemes that will require major upgrading. Erosion of coastal areas: many deltas face a sediment shortage. This sediment shortage is often caused by regulation works in the upstream river. The sediment shortage causes coastal erosion problems. Sea level rise will aggravate these erosion problems. Loss of environmental quality: Ecosystem functioning and biodiversity in deltas is under very high pressure worldwide. Main causes are a high population density and concentration of industrial, harbor and mining activities. Deltas are also receptor of pollutants from upstream.
  12. 12. Trends and issues in the development of deltas Importance of issues in the eight selected deltas The Aquaterra Conference will present and discuss the state and future of deltas worldwide, with a special focus on eight selected deltas: 1. Yellow River Delta (China) 2. Mekong River Delta (Vietnam) 3. Ganges–Brahmaputra delta (Bangladesh) 4. Ciliwung River Delta (Indonesia) 5. Nile River Delta (Egypt) 6. Rhine River Delta (The Netherlands) 7. Mississippi River Delta (USA) 8. California Bay (USA) 12
  13. 13. In the research a quick assessment has been made whether the delta issues are a minor or major problem in these deltas. Box 1.4 displays to what extent issues play a role. The classification distinguishes four types of problems. Problems are judged minor if they are either unimportant, small in magnitude or well controlled (•). A minor problem can become bigger in future (e.g. due to climate change or delta developments) in which case it is given two bullets (••). An issue is classified as a currently big problem if the issue is requiring significant management attention and is not (yet) controlled (•••). If the problem is likely to increase in the near future it is given four bullets (••••). Box 1.4 issues deltas pressure on flood freshwater ageing or coastal loss of space vulnerability shortage inadequate erosion environmental infrastructure quality and biodiversity Yellow River Delta •• • •• • ••• ••• 13 (China) Mekong River Delta •• •••• •••• •• • ••• (Vietnam) Ganges– •••• •••• •• •• •••• •••• Brahmaputra Delta (Bangladesh) Ciliwung River Delta •••• •••• •• •• • •••• (Indonesia) Nile River Delta •••• • •••• •••• •• •• (Egypt) Rhine River Delta ••• •• •• ••• •• • (The Netherlands) Mississippi River • •••• • •••• •••• •••• Delta (USA) California Bay •• •••• •••• ••• • ••• (USA) Legend: • relatively minor problem, now and in the near future •• currently a minor problem, but is likely to increase in the near future ••• currently already a big problem, future trend uncertain •••• currently already a big problem, likely to increase in the near future
  14. 14. Trends and issues in the development of deltas Brief explanation of assessments The assessments presented in Box 1.4 reflects our current understanding of the issues at stake in the eight deltas and may need revision once more information becomes available. A short explanation of the reasoning behind the assessment is presented underneath. The separate delta descriptions provide further background on the issues. Yellow River Delta (China) pressure on space: With a relatively low population density (210 inhabitants/km2 in the rural area) this issue is not urgent vulnerability to flood: Flood risk is relatively low: the river is fully embanked and there is no storm surge hazard freshwater shortage: Although minimum flows for the delta are guaranteed, future climate change is likely to reduce overall water availability in the river basin ageing infrastructure As the delta and its occupation is of recent date, ageing of infrastructure 14 does not play an important role yet coastal erosion: Especially along the northern coast erosion is a big problem due to sediment starvation loss of biodiversity: Nature Protection areas along the coast are under high pressure of limiting freshwater and economic activities (esp. from the oil industry) Mekong River Delta (Vietnam) pressure on space: The population density is 410 inhabitants/km2 and with a growth rate of 2.5% per year, pressure on space will increase in future vulnerability to flood: Floods are a common feature of the delta and society has learned to live with it. freshwater shortage: During low flows salinity intrusion is a recurrent problem, likely to increase with sea level rise. Groundwater use is growing. ageing infrastructure The delta has an extensive canal and embankment system, some of which over 100 years old coastal erosion: The sediment balance of the Mekong river is, compared to other major Deltas, relatively stable
  15. 15. loss of biodiversity: The Delta has an extremely rich biodiversity which is under pressure due to the rapid economic growth Ganges–Brahmaputra Delta (Bangladesh) pressure on space: With some 1500 inhabitants/km2 the delta is one of the most densely populated regions on earth. vulnerability to flood: Most of the delta is prone to tropical cyclones with high storm surges. freshwater shortage: Due to upstream developments and climate change, critical low flow conditions of rivers are likely to increase ageing infrastructure Management of embankments and irrigation system is a recurrent problem coastal erosion: Annual rate of erosion is ± 10,000 ha and accretion is only 2,500 ha. 15 Erosion is a bigger problem than flooding. loss of biodiversity: Especially the mangrove forests (Sundarbans) are highly valuable but also under high pressure from encroachment and exploitation. Ciliwung River Delta (Indonesia) pressure on space: Jakarta is the fourth largest urban area in the world (23 million inhabitants) vulnerability to flood: Almost half of the area is below sea level and is still subsiding. The city is prone to inundation due to excessive rainfall and flash floods freshwater shortage: Land conversion from forest to agriculture and urban area results in water shortages during the dry season. ageing infrastructure Although much of the infrastructure is relatively recent, rehabilitation is needed, esp. with respect to drainage systems coastal erosion: Locally there is coastal erosion due to natural and man-made factors. Islands in the Bay are disappearing as a result of coral reef destruction loss of biodiversity: Water quality is a major issue as many upstream domestic and industrial waste water is discharged untreated.
  16. 16. Trends and issues in the development of deltas Nile River Delta (Egypt) pressure on space: With half of Egypt’s population of 80 million living in the delta and a population growth rate of nearly 2% pressure on available space is the main issue of the Nile Delta vulnerability to flood: River floods are minimized through the High Dam and coastal storms are rather mild. freshwater shortage: The entire country is dependent on Nile water inflow. As demands continue to rise, freshwater shortage will increase in the future. ageing infrastructure The extensive irrigation system is stretched to its limits; there is a constant need for efficiency improvement coastal erosion: Due to Aswan dam most of the Nile sediments are trapped in Lake Nasser. Sediment balance at the coast is disturbed, leading to coastal erosion loss of biodiversity: As the bird-rich coastal lagoons are at the end of the system, their water quality is threatened by salinization and pollution. 16 Rhine River Delta (The Netherlands) pressure on space: With a population density of around 500 inhabitants/km2 the delta is densely populated which implies a high pressure on space vulnerability to flood: Although the flood risk is quite small, potential consequences of a flood are high. Future sea level rise and growing investments will increase flood risk. freshwater shortage: Rising sea levels will increase the problem of salt water seepage and will cause local freshwater shortages. ageing infrastructure The sophisticated infrastructure will require adaptation to new conditions induced by climate change. coastal erosion: Coastal erosion is well controlled with extensive sand nourishments. Sea level rise will increase the maintenance nourishments needs loss of biodiversity: The health of estuarine and coastal ecosystems is compromised by pollution and reduced hydrodynamics. Plans are underway to improve the situation.
  17. 17. Mississippi River Delta (USA) pressure on space: The population is not very dense, less than 100 inhabitants/km2. vulnerability to flood: The delta is recurrently visited by hurricanes. The flood protection system requires upgrading. freshwater shortage: As yet there is no serious shortage of freshwater in the Delta. ageing infrastructure There is a high investment need to upgrade the flood protection and navigation (the Mississippi River Gulf Outlet, MRGO) system. The MRGO is a former federal navigation channel opened in 1968 to provide a short route between the Port of New Orleans and the Gulf of Mexico. coastal erosion: Soil subsidence, canal construction and wave exposure have led to huge land loss. Likely to increase due to sea level rise. loss of biodiversity: Wetlands are disappearing at an alarming rate since decades. California Bay (USA) 1 pressure on space: Pressure on the available space is currently not a major issue. But population growth rates in the Delta are projected to be higher than in the state as a whole. vulnerability to flood: Most of the delta is below sea level. Sea level rise, earthquake hazard and subsidence will increase vulnerability. Large scale flooding of the Delta with saline water could have immense consequences for the entire state. freshwater shortage: Nearly two-thirds of the state’s population depend on the Delta for at least some of their water supply. The delta experienced severe droughts in the past. Limited opportunities to increase supply. ageing infrastructure Delta infrastructure started to develop as from 1850. Because of shifting demands it requires constant updating and maintenance. coastal erosion: The delta itself does not have a coast. In the wider region (San Francisco Bay) several beaches suffer from erosion loss of biodiversity: The Delta is in an ecological tailspin. Invasive species, water pumping facilities urban and agricultural pollution are degrading water quality and threatening multiple fish species with extinction.
  18. 18. Trends and issues in the development of deltas The main purpose of the overview of Box 1.4 is to show that there is quite some variation between the eight deltas. For example vulnerability to flooding is a major issue in most deltas but not in all. The table also shows that some deltas have to deal with a range of major issues, whereas in other deltas most issues are minor or at least under control. Although some individual assessments may need further study , this will not alter the overall picture. 1.4 Conceptual view on planning of delta development The delta issues described have something in common: they reflect development of land and water use and development of infrastructure which was not sustainable. In other words the developments were not in harmony with the limitations and potentials of natural systems. To analyze the sustainable development of deltas a framework of analysis is needed. In this research the so-called ‘Layer modeli has been adopted (see Figure 1.1). The Layer model divides the space in three physical planning layers, each with their 1 own dynamics. These layers are the base layer (water and soil), the network Figure 1.1 Layer model for planning of delta development
  19. 19. layer (infrastructure) and the occupation layer (physical pattern arising from human activities: living, working, recreating; in short: land and water use). The essence of the Layer model is the difference in dynamics and vulnerability between the layers, which results in a logical order in planning the various layers. The layers enable and/or constrain activities in another layer. The Layer model may be instrumental in for example the design of strategies for adaptation to climate change. The key to adaptation to climate change (climate proofing) lies in the base layer. If the structure of the base layer is climate proof, then the other layers follow suit. This is not a matter of hierarchy or dominance but of logical order: the base layer first. The climate proofing of the base layer is the sole responsibility of government. The way to act is to make maximum use of the large adaptive capacities of natural systems. Moving to the occupation layer the role and influence of government becomes more restricted and the influences of private parties and citizen’s interests become more dominant. 1 1.5 A closer look at some societal trends Privatization In many countries governments tend to pull away from ownership and management of infrastructure. The central government increasingly plays a role of coordinating networks and markets and organizing supervision (Broekhans Correljé, 2008). Public-private partnerships are becoming more and more the modus operandi for new infrastructural projects. Utility sectors, such as railways, electricity and drinking water have been privatized in many countries. Increased efficiency of tax payer’s money is a key motive for this development. But that does not mean that there is no role left for the central government. Indeed, in order to safeguard public values in the liberalized utility sectors, authorities are installed that oversee quality and guaranteed delivery of goods and services. Another form of privatization is the handover of land (and water) that was previously owned and managed by the government. Examples can be found in Eastern European and some Asian countries. These countries are now under transition from a previously communist regime to a more democratic
  20. 20. Trends and issues in the development of deltas and capitalist economy. This transition has often increased the much needed agricultural productivity, but also created new ‘tragedies of the commons’. For instance, in Vietnam, liberalization of market forces and privatization of coastal resources has led to serious cases of overexploitation (Kleinen; Adger Luttrell, 2000). A case study from the Red River Delta revealed that privatizing water management institutions does not necessarily mean a better management of water (Fontenelle, 2000). Decentralization Decentralization of planning and management is visible in many countries as well. For example in India decentralization is taking place through the Panchayat system (i.e. local government bodies at the village level). There can be different reasons for downscaling management and planning at more regional and local levels: e.g. reduction of government bureaucracy, increased empowerment and participation of local stakeholders, state budget constraints and political motivations. Although most people generally agree that it is better to decide and manage at the lowest possible level (e.g. subsidiary principle: the idea that 20 a central authority should have a subsidiary function, performing only those tasks which cannot be performed effectively at a more immediate or local level (Wikipedia, accessed on 3 December 2008), this does not mean that this goes without any problems. For instance, a study on the decentralized management of fishery and wetland resources on the Kerala Coast (India), concluded that ‘fisheries is the big looser in the local self-governance system’ (Panday, 2003). Although intentions are often good, the elaboration of clear roles and human capacity are often the bottleneck. Global environmental concern Global climate change poses both risks and opportunities: worldwide concern over a changing climate and environmental degradation has raised an environmental awareness that was not seen before. The Intergovernmental Panel on Climate Change, the UN Millenium Development Goals, global conventions on biodiversity, wetlands and transboundary pollution and the World Water Forum are but a few of the examples that exemplify this awareness. This leads to the notion by many people that human society needs to adapt to the (limiting) carrying capacity of the environment, i.e. the ‘base layer’ in our conceptual model. Dealing with these trends These trends pose tremendous challenges to delta management. Existing
  21. 21. management approaches and tools are not always adequate as they tend to tackle these challenges in a piecemeal and sector wise way. For example, in many countries a full fledged Environmental Impact Assessment legislation is operational. Although this is a great improvement over past practices neglecting the negative consequences of development projects, it mostly does not account for multiple and cumulative impacts. Also planning regulations and limitations do not always serve an optimal spatial development. And sometimes even are counter effective. For instance, hazard regulations that could promote risk reduction in the long run, could turn into vehicles for short- term and short-sighted economic gain. We see this in communities that rush to issue permits before the publication of new maps that show that the area to be built in is vulnerable to an increased or changed flood hazard (Armstrong, 2000). It has also been long standing knowledge that nature conservation by means of protective areas or reserves has significant limitations. Endangered species get trapped in those isolated havens as their habitat becomes unsuited due to climate change. These are but some examples of the difficulties delta management is confronted 21 with. As a way out, a more holistic and integrated view on delta management is getting shape. We see this for instance in integrated water management, coastal zone management and at the scale of entire river basins. But there is more: ideas to reconcile human development with nature are emerging in various fields. ‘Building with Nature’ is practiced already in the form of beach nourishments as opposed to hard structures to control erosion. Multifunctional use of infrastructure is being implemented in densely populated deltas, to save space and money. Restoring the natural purification capacity of wetlands and estuaries are being considered in highly modified deltas, as in the Netherlands. Renewable energy from waves, tides and salinity gradients is being studied. Decentralization and privatization may be viewed as autonomous developments. The challenge is to utilize the advantages of both trends, while minimizing their undeniable drawbacks. This calls for a selective enhancement of governance structures, reflecting the regional scale, integrated nature and long term perspective of delta development. 1.6 Linking responses to drivers and trends To promote sustainable development of deltas a clear vision has to be developed on how to respond to the various drivers of change as well as on how to play along
  22. 22. Trends and issues in the development of deltas with the various trends in society. A strategy for sustainable development of deltas cannot be limited to infrastructural measures or restoration measures for natural systems. A sensible combination of different kind of responses is required. This should include measures for management and restoration of natural systems, for development and adaptation of land and water use and for extension and revitalization of infrastructure. Furthermore enhancement of the governance structure is required to enable implementation of these responses. These are in fact the four major response themes distinguished in the Aquaterra 2009 Conference (see Figure 1.2). The first three response themes reflect the three layers of the conceptual planning model. The research has explored the perspectives of and experiences with these response themes. Some of these responses may already be classified as ‘best practices’, others are yet promising approaches. Anyway, the research provides an overview of current practices in dealing with delta issues. An effort has been made to arrange these practices into trends. These trends are 22 discussed by response theme in the next sections. Figure 1.2 Linking response themes to drivers and trends
  23. 23. 2. Management and restoration of natural systems 2.1 Functions and values of deltas Delta processes: shaping the base layer Deltas are relatively young landforms shaped by the interplay of coastal and riverine processes. For example the entire Yellow River Delta was formed in a period of slightly more than century. Since 1855, when the Yellow River shifted its course from debouching in the Yellow Sea towards flowing into the Bohai Sea, each year up to several thousands of hectares of new land was formed (Liu Drost, 1996). This rapid expansion of the delta is thanks to the enormous 23
  24. 24. Management and restoration of natural systems quantities of sediment transported by the Yellow River from the extensive Loss plateaux and from which the river has received its name. Although the Yellow River is quite exceptional in its sediment load, all other deltas have been formed by the sediments brought in by their respective river and shaped by the interplay of tides, waves and currents. At the seaside of a delta, these forces tend to erode and disperse the sediments. But as long as the net input of sediments exceeds the rate of erosion, the delta will grow. This brings us to the first important observation: these natural processes are crucial in the long term evolution of a delta. A net deficit in sediment supply will lead to coastal erosion and – hence – could lead to problems in the human use of the delta base layer. Besides sediments, the river also constantly supplies the delta with fresh water, nutrients and organic matter. When the freshwater mixes with the seawater, flocculation leads to rapid settling down of small particles and produces an extremely nutrient rich aquatic environment. For this reason the delta estuaries and its marine environs have the highest biological production of all natural areas in the world. From this wealth, economic benefits are reaped in the form 24 of fish, shellfish and other seafood. And by the way, it also explains the highly prized occurrence of oil and gas stocks under present day deltas: these are the fossil remains of the organisms that once thrived in the similarly productive coastal waters. Table 2.1 Official Ramsar sites in deltas Delta Site Size Nile Delta Lake Burullus 46,200 ha Ganges Sunderbans 601,700 ha Rhine Delta all open and closed estuaries (10 sites) 188,475 ha Rhone Delta Camargue La Petite Camargue 122,000 ha Ebro Delta entire delta 7,736 ha Danube Delta entire delta 647,000 ha Volga Delta entire delta 800,000 ha Senegal Delta Parc National du Diawling 15,600 ha Red River Delta Xuan Thuy Natural Wetland Reserve 12,000 ha
  25. 25. It is not surprising that these rich deltas attract migrating birds. Lying at strategic positions along flyways, delta nature sites are key stepping stones of millions of birds en route from north to south and vice versa. At this moment some 2,4 million hectares of delta wetlands have been given the official status of Ramsar Site, indicating that these wetlands are of international importance for the survival of many bird populations (see Table 2.1). In three instances, even the entire delta has been designated as official Ramsar site, viz. the Ebro, Danube and Volga delta. Functions and values for mankind Deltas are a gift of nature to mankind. Deltas have flat, highly fertile soils that are easy to till. They can be travelled across on its waters, full of fish. But as the Table 2.2: major ecosystem functions in deltas Category Function Ecosystems and mechanisms (main examples) 25 Regulation functions Storm and flood Mangroves, coral reefs, salt marshes, dunes, protection etc. CO2 sequestration Forests Nutrient cycling Estuarine denitrification Soil formation delta development (sediment deposition etc.) Habitat functions Refugium function Suitable living space for wild plants and animals Nursery function Suitable reproduction habitat (e.g. mangroves as nursery for fishshrimp) Production functions Food production Fishery agriculture Raw materials Sand and clay / wood Energy production Tidal energy Wind energy Information functions Recreation tourism Beach recreation Watersports Eco-tourism
  26. 26. Management and restoration of natural systems sea gives, it can also take. Their low lying topography make deltas vulnerable to storm surges and river floodings. And if not from aside, the seawater enters from below: seepage of saline groundwater poses a constant threat to the crops. Hence, man has to dig and develop. Land reclamation, irrigation, soil drainage and embankments have made many a delta hospitable: a place to safely live in and to live off the fruits of the land and sea. Several of the deltas have developed into the major granary or rice bowls of an entire country, such as the Red River Delta in Vietnam and the Godavari and Krishna deltas in India. A generic classification of functions and values of nature and natural processes is given by (de Groot et al., 2002) and distinguishes regulation-, habitat-, production- and information functions. Nature provides these functions, free of cost, to mankind. In deltas, ecosystems provide the following major functions (Table 2.2): Table 2.2 shows that for instance ‘Storm and flood protection’ is provided by delta ecosystems that include mangroves, coral reefs, dune systems and salt 26 marshes, but can also include coastal forests, seagrass beds, intertidal flats, and lagoons, depending on the delta in question. Mechanisms for regulating storm and flood impacts in coastal areas include: wave dissipation, barrier to flood surge, wind breaking, coastal accretion and stabilization (long-term) and regulation of sediment transport linked with coastal geomorphology. Obviously, coastal ecosystems can perform several of these functions simultaneously: a mangrove forest protects land from a storm surge, it provides a nursery area for fish and shrimp, it yields useful timber and serves as a habitat for many species including migrating birds. Section 2.5 presents several examples of multifunctional uses. How much are these functions worth? One well known study has estimated ‘Estuaries have the the monetary value of the world ecosystems. In this study, (Costanza et al., 1997) calculated that estuaries have the highest economic value of 22,832 highest economic US $ ha-1 year-1 of all ecosystems. Nutrient recycling and food production are the major functions that contribute to their high economic value. Off shore value of all seagrass and algae beds closely follow with 19,004 US $ and tidal marsh/ mangroves contribute a respectable 9,990 US $. These figures become all the ecosystems’ more significant when compared with, for instance, tropical forests (2007 US $) and open oceans (252 US $). These figures signify the enormous relative importance coastal and delta ecosystems have for humankind.
  27. 27. Status and trends in delta values and functions The most important direct drivers of change in ecosystems worldwide – and probably also for delta ecosystems – are habitat change, overexploitation, invasive alien species, pollution and climate change. Habitats are converted to agricultural land or shrimp ponds and especially fish stocks are overexploited. Alien species and disease organisms continue to increase because of both deliberate introductions and accidental translocations through commercial shipping related to growing trade and travel, with significant harmful consequences to native species and many ecosystem services. With respect to pollution, particularly the nutrient loading to regional seas is disturbing: Excessive flows of nitrogen contribute to eutrophication of freshwater and coastal marine ecosystems. For instance, there has been an 10 fold increase in nitrogen flux of the Yellow river to the sea since the industrial and agricultural revolutions and for the North Sea watersheds this is even a 15-fold increase. Table 2.3 Drivers of coastal change (source: (Agardy Alder, 2005) 2 Habitat Loss or Conversion Habitat Degradation Overexploitation Coastal development (ports, Eutrophication from land- Directed take of low-value urbanization, tourism-related based sources (agricultural species at high volumes development, industrial sites) waste, sewage, fertilizers) exceeding sustainable levels Destructive fisheries (dynamite, Pollution: toxics and Directed take for luxury cyanide, bottom trawling) pathogens from land based markets (high value, low sources volume) exceeding sustainable Coastal deforestation (especially levels mangrove deforestation) Pollution: dumping and dredge spoils Incidental take or bycatch Mining (coral, sand, minerals, dredging) Pollution: shipping-related Directed take at commercial scales decreasing availability of Civil engineering works Salinization of estuaries due resources for subsistence and to decreased freshwater inflow artisanal use Environmental change brought about by war and conflict Alien species invasions Aquaculture-related habitat Climate change and sea level conversion rise
  28. 28. Management and restoration of natural systems Indeed, compared to other types (such as forests, drylands and mountains), worldwide coastal ecosystems have been most impacted over the last century by all of these drivers and current trends are increasing (MEA, 2005). In Table 2.3 a description of the major drivers of change on the delta ecosystems have been indicated. Loss of habitat can occur through a variety of causes, but the majority of habitat loss in delta environments is the conversion of freshwater- and salt marshes into agricultural land (for instance through land reclamation) and – in the tropics – the conversion of mangroves into aquaculture. Worldwide decline in mangrove forest is estimated to be around 2% per year between 1980 and 1990 and 1% per year between 1990 and 2000 (Lewis III, 2005). In the 18th century the Sundarbans of Bangladesh (the largest single mangrove forest in the world) was twice its present size, which was lost to agricultural lands of the adjoining landlords (Chowdhury and Ahmed, 1994). But also a more complex set of factors can lead to reductions in original delta 2 habitats. For instance, the combination of subsidence, incidental hurricanes and the construction of levees and canals (for the oil exploration and navigation) has led to massive reduction in Louisiana’s coastal wetlands. An area the size of a football field disappears every 35 minutes (National Geographic News, 2005). Louisiana had already lost 1,900 square miles of coastal lands, primarily marshes, from 1932 to 2000. 217 square miles of Louisiana’s coastal lands were transformed to water after Hurricanes Katrina and Rita (USGS, 2006; USGS reports on latest land change estimates for Louisiana coast; USGS News Release, October 3, 2006). Estuarine systems are among the most invaded ecosystems in the world. Often introduced organisms change the structure of coastal habitat by physically ‘sea level rise is displacing native vegetation. For example, San Francisco Bay in California has over 210 invasive species, with one new species established every 14 weeks probably the most between 1961 and 1995. Most of these bio-invaders were brought in by ballast water of large ships or occur as a result of fishing activities. (Agardy Alder, important climate 2005) change induced Of all potential impacts of a rising global temperature, sea level rise is probably the most important for deltas. Combined with subsidence of the delta soils, sea factor for deltas’ level rise can lead to a series of changes in the delta environment. It increases coastal erosion, thereby threatening human settlements and enlarging the
  29. 29. risk of coastal flooding. But sea level rise also leads to landward movement of the tidal influence and salt wedge in rivers, which jeopardizes freshwater intakes for agricultural, industrial and domestic water supply systems. That coastal erosion can also occur without a change of climate, is a well known fact. It has everything to do with the sediment balance within a coastal cell, which can be disrupted by natural and human-induced causes. A good example of the latter is the increased erosion along the Nile Delta after the completion of the Aswan High Dam (see Figure 2.1). Compared with the past five decades, both river discharge and sediment load will probably decrease for some large river systems with 30-40% in the next 50 years and decrease up to 50% in the next 100 years as a result of 2 Figure 2.1: Coastal erosion Nile Delta: coastline changes in Egypt between 1935 and 1985 (from West Damietta to West Port Said)
  30. 30. Management and restoration of natural systems human activities and dam construction. Thus general erosion in the coastal zone, including estuaries, deltas and associated beach systems seems to be inevitable (Agardy Alder, 2005). What can we do about it? The good news is that delta ecosystems can be relatively easily restored. Because the delta environment is highly dynamic, delta nature has a ‘the good news remarkable adaptive and resilient capacity. In contrast to for instance tropical rainforests which require centuries to reach a climax succession stage, delta is that delta ecosystems such as salt marshes, mangroves and dunes develop quickly into rich habitats once the environmental conditions are favourable. ecosystems can be All over the world we see restoration ideas turning into reality. Of course not relatively easily every initiative is an immediate success. There is much trial and error. But the most important thing is that people see the need to protect their environment restored’ and to work with nature instead of against it. In this chapter a number of these initiatives will be presented, some of them still in its early conceptual stage, 30 but others already worked out in practice. These best practices show the importance of: • Good knowledge of the basic physical and ecological processes; • Early involvement of local stakeholders leading to a participatory planning process; • An integrated approach We have selected experiences that illustrate different ways of combining ecosystem functions for the benefit of society. In the next section we will show how nature can help in protecting the coast, by soft and ecological engineering. Then we present examples that demonstrate the benefit of safeguarding the integrity of coastal ecosystems by restoring estuarine dynamics and guaranteeing a minimum river flow. We proceed by presenting a showcase in the ‘Room for Rivers’ philosophy and we conclude with examples of the multiple use of wetlands.
  31. 31. 2.2 Natural coastal protection and wetland restoration There is ample evidence that coastal protection can greatly benefit from a resilience based approach. Many of the world’s coastlines are highly dynamic by nature through the forces of winds, waves and currents. Hard engineering structures have more often than not led to increased erosion, either on the location itself, or at nearby, unprotected beaches. Instead, coastal practitioners are increasingly applying soft engineering measures, such as beach and foreshore sand nourishments. Modern modelling and surveying techniques are used to optimise these nourishments, whereby the question is how to best make use of the prevailing local physical conditions. A new approach of ‘super- nourishments’ is currently being under study in the Netherlands (see Box 2.1). Box 2.1 Rhine case: sand nourishment through pilot of Sand engine, suppletion strategy from new Delta committee 31 Sand nourishment is the mechanical placement of sand in the nearshore zone to advance the shoreline or to maintain the volume of sand in the littoral system. It is a soft protective and remedial measure that leaves the coast in a more natural state than hard structures and preserves its recreational value. The method is relatively cheap if the borrow area is not too far away (10 km) and the sediment is placed at the seaward flank of the outer bar where the navigational depth is sufficient for hopper dredgers. Three types of nourishments are distinguished: beach-, shoreface- and dune nourishments (Van Rijn, 2008). It should be noted that these kinds of measures need to be repeated every few years, because due to wave and current forces, these nourishments will be gradually spread out to the onshore and offshore direction. Typical lifetime of a normal shoreface nourishment is in the order of 5 years (Van Rijn, 2005). Therefore, also other alternative techniques of nourishments are being studied. At this moment the potentials and risks of a ‘super-nourishment’ called ‘The Sand Engine’ in front of the Dutch coast (shoreface) are being investigated. Although the current beach nourishments are successful and effective for local coastline maintenance, such a super-nourishment could turn out to be more efficient in serving more functions than safety alone. The idea is to apply an extra amount of sand that would be redistributed by nature itself, thus stimulating natural dynamics of the coast, increasing a bufferzone for future sea level rise and enlarging the coastal intertidal zone which is beneficial for natural and recreational values alike.
  32. 32. Management and restoration of natural systems Besides and in addition to these sand nourishments, also ecological Ecological engineering is being practiced. From the notion that mangroves can provide effective storm protection (see Box 2.2), there is increased attention to restore engineering these coastal forests. Great potential exist to reverse the loss of mangrove forests worldwide through the application of basic principles of ecological approaches offer restoration using ecological engineering approaches. Mangrove restoration can be successful, provided that the hydrological requirements be taken into great potential account, which means that the best results are often gained at locations where mangroves previously existed, such as abandoned) aquaculture ponds (Lewis III, 2005; Stevenson et al., 1999; Samson Rollon, 2008). 32 Figure 2.2: Mangrove seedlings waiting for transplantation (Banda Aceh, Indonesia)
  33. 33. Box 2.2 Example of storm protection by mangroves Since 1822, a total of 69 extreme cyclones landed on the Bangladesh coast of which 10 hit the Sundarbans mangrove forest. However, a cyclone that lands on the Sundarbans causes less damage compared to the likely damage caused the cyclone of equal magnitude lands on the central and eastern part of the coast. Most of the cyclone damage is caused by the surge. For example, a cyclone that landed on the Cox’s Bazar coast generated 4.3 m surge caused deaths of 11,069 people in 1985. On the other hand, when a similar cyclone landed on the Sundarbans in 1988, the number of fatalities was just half of the 1985 cyclone (MEA, 2005). 2.3 Integrity of ecosystems: biodiversity, environmental flows In our relentless effort to reshape our coastal environment for our own benefit, 33 we sometimes forget that everything has its price. Besides the profits we gain, there are also losses to sustain. But instead of accepting these losses in biodiversity and ecological functions, there are ways to restore the integrity of ecosystems. This does not necessarily require a complete restructuring of the original situation, but can also lead to a rejuvenation or improvement of already modified ecosystems. A good example is the restoration of estuaries by reconnecting them with rivers and sea without compromising the attained high safety against flooding in the Rhine Delta of the Netherlands (Box 2.3). Setting and Ensuring the integrity of the linkages between delta and river often also requires measures upstream. Developments in the river basin, such as deforestation, maintaining irrigation and hydro-power generation dams all exert an influence on the well-being of delta ecosystems. Sediment loads change, freshwater inflows environmental often reduce and persistent pollutants accumulate. Recently new insight has been gained with respect to the importance of freshwater inputs in coastal flow requirements ecosystems. Seasonal changes in river flow can temporarily change the ‘normal’ condition of an estuary. Usually the estuarine ecosystems and their promotes the species are adapted to this highly dynamic environment as long as these seasonal variations remain within the average natural dynamics. Upstream integrity of water diversions can permanently change this pattern with significant consequences for the estuarine ecosystem. Establishing an environmental ecosystems
  34. 34. Management and restoration of natural systems flow requirement is being considered as an important management measure to guarantee the integrity of downstream ecosystems. An example of how this is done is presented for the Yellow River Delta (see Box 2.4) Box 2.3 Restoration of estuarine dynamics in the Rhine Delta, The Netherlands The Southwestern delta has a long history of embankments. Embankments have a twofold effect. Inside dike rings, active sedimentation is excluded and thus dike rings must be considered to be completely sediment starved. Moreover, soil compaction, peat oxidation and drainage lead to self perpetuating land subsidence. Increasing saline seepage is one of the side effects. Outside the dike ring, in the estuaries, storm flood levels increase due to the decreased basin storage. The cumulative effect of sediment starvation, land subsidence, sediment export and sea level rise is an enormous historical sediment deficit, defined as the negative difference between land surface and Dutch ordnance datum (NAP). The total deficit for the Dutch lowlands is estimated at 13.3 km3 (vd Meulen et al., 2006). The sediment deficit for the delta area is illustrated in figure 2.3, comparing the land 34 surface in the delta anno 1000 and the land surface above sea level in the delta at present. Figure 2.3: Comparison land surface above sea level delta anno 1000 and 2000 The reshaping of the formerly morphologically dynamic delta into a completely petrified landscape, eliminating adaptiveness and resilience, indeed has its price! And the bad message is that there is no way back. Morphodynamics cannot be reintroduced without jeopardizing safety against flooding. History commits to continued and even increasing dependency on flood defenses.
  35. 35. As a consequence of the last great flood in 1953 the Dutch government decided to close off most of the Delta estuaries, turning them into stagnant salt or freshwater lakes. Although safety from flooding was greatly enhanced, it turned out that these new ecosystems did not develop satisfactory. In the closed estuaries, shoreline erosion forms a threat for the remaining terrestrial and transitional zones between the dike and water. In the remaining open estuaries, the Eastern and Western Scheldt, the vulnerability of salt marshes to erosion also increased: in the Eastern Scheldt because of the diminished tidal influence, and in the Western Scheldt because of dredging operations to maintain a deep channel as shipping route to Antwerp. ROTTERDAM NIEUWE WATERWEG HARINGVLIET GREVELINGEN HOLLANDSCH 35 DIEP KRAMMER-VOLKERAK OOSTERSCHELDE ZOOMMEER MIDDELBURG VEERSE MEER BERGEN OP ZOOM MARKIEZAATSMEER VLISSINGEN WESTERSCHELDE TERNEUZEN ANTWERPEN BRUGGE Figure 2.4: Summary of measures to restre estuarine dynamics
  36. 36. Management and restoration of natural systems Besides these morphologically induced problems most waters also suffer from an impoverished water quality. Many of the closed-off water bodies, like for instance brackish Lake Veere and saline Lake Grevelingen, experience stratification and anoxia in deeper layers, mainly because of reduced refreshment and long water residence times. The worst situation exists in the freshwater Lake Krammer-Volkerak, where eutrophication processes caused by agricultural run-off lead to a very bad water quality with extensive scums of blue green algae. Some years ago, the provincial managing authorities have drafted a vision for the future, in which the restoration of estuarine dynamics has a prominent place. Central to this vision is to partially restore the tidal dynamics and/or to restore the link with the rivers, while maintaining the same level of safety. This will start the water flowing again, which improves the natural turnover of nutrients and production of shellfish, fish and birds without the nuisance of algal blooms. Each water body in the Delta requires its own approach. Although the first sluice between Lake Veere and the Eastern Scheldt has opened already back in 2004, it will take many years to complete the implementation of this new vision. 36 Box 2.4 Yellow River Delta: environmental flow requirements to protect downstream water uses Fresh water is of key importance for many economic activities in the Yellow River Delta. It is used as drinking water, for growing crops, for industrial activities and for maintaining healthy ecosystems. Of all consumers, the irrigated agriculture has the highest demand, which is not surprising because of the high evaporation rate during most of the year. This evaporation surplus causes capillary rise of the saline groundwater into the top soils, which has to be flushed with fresh water. Currently around two third of the Delta area has moderate to serious salinity problems. The most important source of freshwater is the Yellow River. But unfortunately, the Yellow River basin is very deficient in water resources. The conflict between supply and demand is prominent. Especially since 1992 annual discharges of the lower Yellow River reached dangerously low levels, leading to frequent periods of zero discharges of more than 100 days per year. From 1995 to 1998, the river was dry during more than 120 days every year, up to as much as 226 days at Lijin in 1997. This regular drying up of the lower Yellow River had serious impacts on the downstream socio-economic functions and caused large ecological damages in the delta. Therefore, the Yellow River Conservation Commission (the basin wide administrative agency) has implemented a regulated discharge regime of the river since 1999, in order to recover the river stretches downstream of Lijin (Liu Xiaoyan et al., 2006). This relieved the risk of drying up and the water deficiency in the lower delta to some extent.
  37. 37. However, there is still a long way to go to the optimal allocation of water resources required by all economic sectors and the ecosystems of the delta (Liu Gaohuan Drost, 1997; Liu Gaohuan, 2006). Until recently, for the Yellow River, little was known about the exact water demand for ecological system development of the delta and about the ecological effect and influences of allocation of water. Especially, proper identification of the habitats demanding water in the delta was lacking, as well as the amount of water needed to restore damaged wetland ecosystems and to maintain sustainability of the delta ecology (see e.g. Guan Yuanxiu Liu Gaohuan, 2003). A recent study on the water allocation for the two Nature Reserves in the lower Yellow River Delta revealed that the total future water requirement that includes domestic, industrial, agricultural and restored wetland demands is less than 10% of the annual average river discharge at Lijin. Although this suggests that there is ample water, the situation could be different in the months of March, April and May. During this low flow period the water demand is typically at its highest and critical situations (e.g. in dry years) are not ruled out. This exemplifies the need for an optimization of water requirements through daily water management (Lian Yu et al., 2007). 3 2.4 Room for rivers For centuries rivers have been harnessed to make better use of them. Normalisation and canalisation have straightened and narrowed naturally meandering and braided river systems into a single channel system, benefiting navigation for increasingly bigger ships. Embankments were raised to reduce flooding frequencies of the adjacent lands, which became more and more populated. Over the past decades the adverse consequences of these river ‘Room for rivers’: engineering measures became apparent. Natural values have greatly declined and river beds eroded, leading to undermining of sluices and bridges. Groynes a more resilient and the narrowing of the floodplain impeded a rapid discharge of water and ice, increasing the risk of flooding. As climate change could result in higher strategy for flood peak discharges, river managers were confronted with the question to further heighten the sea defenses or exploring other possibilities. The ‘Room for risk management Rivers’ concept, giving back the areas of natural horizontal expansion during floods through wideing of floodplains and creation of retention areas, was born out of a belief that it is better to opt for a more resilient strategy than to go for resistance against the forces of nature. The Rhine programme in the Netherlands is a showcase for this new philosophy and supports the paradigm shift from ‘fighting the floods’ to ‘living with water’.
  38. 38. Management and restoration of natural systems Box 2.5 Rhine programme ‘Room for Rivers’ High discharges of the Rhine and Meuse Rivers in 1994 and 1995 have led to a significant shift in dealing with safety against river floods in the Netherlands. The age old practice of raising and strengthening of embankments along the rivers is replaced with a new approach, giving more room to high waters. This so-called room for rivers policy contains a wide range of measures, such as lowering of floodplains, creation of side channels, lowering of groynes, river dredging and realignment of dikes. Dike strengthening has become a last option, if other interventions prove to be technically or financially impossible. Most of these measures will have significant consequences on regional and local spatial planning. This makes public participation in planning of flood management strategies crucially important. It also calls for a more integrated planning, thereby combining safety objectives with other policy goals, such as nature development, landscape quality improvement and economic prosperity. The new management policy is now being implemented over the entire stretches of the Dutch parts of Rhine and Meuse in a multi-billion Euro programme. Besides practical innovations in river management, the programme is also innovative with respect to its planning approach of 3 ‘central direction and decentralised implementation’. This creates opportunities for innovative public private partnerships, such as Design Construct agreements, in which planning and implementation is dealt with through one contractor. This requires great adaptation skills from both contractor and government agencies, and a path of trial and learning. The programme has to be finished in 2015. Figure 2.5: River improvement measures in Room for Rivers concept
  39. 39. 2.5 Multiple use of wetlands As coastal wetlands can perform different functions, this means that they do not necessarily need to be protected by denying access. Local people often have used these ecosystems for centuries and are eager to continue doing so. But how can this use be allowed without compromising the integrity of wetlands, without leading to overexploitation of the natural resource? This problem can be tackled by using the ‘ecosystem approach’. This approach is advocated by the Convention on Biological Diversity and denotes a strategy for the integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way. It is based on the application of appropriate scientific methodologies focused on levels of biological organization which encompass the essential processes, functions and interactions among organisms and their environment. It recognizes that humans, with their cultural diversity, are an integral component of ecosystems (website Convention on Biological Diversity). Below three examples are given of multiple use of wetlands. Box 2.6 illustrates Ecosystem the values of Xuan Thuy Ramsar reserve in the Red River Delta, Vietnam. 3 Because of weak management these values are presently under great pressure. approach for a wise The second example (Box 2.7) is considered as a world-renowned model for multiple use of wetlands: the East Calcutta Wetlands. And the last example multiple use of (Box 2.8) is the restoration of infertile, acid sulphate soils (a widespread problem in several tropical deltas and coasts) by the replanting of the original wetlands vegetation, such as the Melaleuca trees in the Mekong delta. Box 2.6 Example of a multifunctional value Ramsar site Xuan Thuy Natural Wetland Reserve. 20/09/88; Nam Ha; 12,000 ha; 20º10’N 106º20’E. Strict Nature Reserve. Delta and estuary islands supporting the last significant remnants of coastal mangrove and mudflat ecosystems in the Red River Delta; includes land enclosed by sea dikes, with fringing marshes. A critically important area for migratory waterbirds and shorebirds, regularly supporting several globally threatened species. Human uses include fishing and aquaculture yielding up to 10,300 tonnes per year, rice production yielding 40,000 tonnes per year, duck rearing, bird hunting, and reed harvesting. The mangrove forest is of considerable importance in maintaining the fishery, as a source of timber and fuelwood, and in protecting coastal settlements from the full impact of typhoons. Ramsar site no. 409. Most recent RIS information: 1992.
  40. 40. Management and restoration of natural systems Box 2.7 Example of a multiple use wetland: East Calcutta Wetlands. West Bengal (12,500 ha). World-renowned as a model of a multiple use wetland, the site’s resource recovery systems, developed by local people through the ages, have saved the city of Calcutta from the costs of constructing and maintaining waste water treatment plants. The wetland forms an urban facility for treating the city’s waste water and utilizing the treated water for pisciculture and agriculture, through the recovery of nutrients in an efficient manner - the water flows through fish ponds covering about 4,000 ha, and the ponds act as solar reactors and complete most of their bio-chemical reactions with the help of solar energy. Thus the system is described as “one of the rare examples of environmental protection and development management where a complex ecological process has been adopted by the local farmers for mastering the resource recovery activities” (RIS). The wetland provides about 150 tons of fresh vegetables daily, as well as some 10,500 tons of table fish per year, the latter providing livelihoods for about 50,000 people directly and as many again indirectly. The fish ponds are mostly operated by worker cooperatives, in some cases in legal associations and in others in cooperative groups whose tenurial rights are under legal challenge. A potential threat is seen in recent unauthorized use of the 40 waste water outfall channels by industries which add metals to the canal sludge and threaten the edible quality of the fish and vegetables. Ramsar site no. 1208. Most recent RIS information: 2002. Box 2.8 Melaleuca wetlands for provision of ecosystem services in the Mekong delta Currently about half of the Mekong Delta has acid sulphate soils, as a result of drainage of wetlands and the expansion of aquaculture and canals. This severely limits the agricultural potential of the delta. Recent research on ecosystem functioning has helped build understanding of how environmental and economic benefits can be simultaneously achieved. In particular, research has demonstrated the role of Melaleuca trees (Melaleuca cajuputi) in improving water quality, thereby lowering the acidity of soil in surrounding fields. The relationship between depth of water in the Melaleuca wetland forest reservoir and days of irrigation needed for good soil quality has been established. This discovery makes it possible to use Melaleuca to lessen the acidity of affected soils and increase agricultural production.
  41. 41. 3. Extension and revitalization of infrastructure 3.1 Role of infrastructure in delta development Living in deltas has always required human intervention. Infrastructure was developed to adapt the natural systems to create more favourable conditions for living and working in deltas. Traditionally the development and maintenance of infrastructure has been the task or responsibility of governments. A responsibility which is more and more shared with other parties through public-private partnership. 41
  42. 42. Extension and revitalization of infrastructure Demographic and economic development lead to a growth in the number of people and economic activities to be served and protected. As a consequence demands on the infrastructure will grow. There are also trends in society and governance to reckon with in the development of infrastructure, such as environmental; concerns, privatization and decentralization. At the same time, the vulnerability of deltas is increasing because of rising sea levels, subsiding soft soils, and increasing pressure on space and environment. Dealing with all these developments together is a complex and challenging task. There are basically two options to respond to the increase in vulnerability: (i) adapting land and water use or (ii) adapting the infrastructure. Box 3.1 Development of infrastructure in The Netherlands: a short history The Dutch history of human intervention in deltas is a history of land reclamation and flood protection. Huge areas of land were already reclaimed in the 17th and the 18th centuries, thanks to technological and economic developments. At the end of this period, large water bodies had been transformed into productive agricultural land, partly by reclaiming broad meres and lakes, partly by reclaiming 42 silted up land outside the dikes. Improvements in drainage techniques enhanced the quality of the reclaimed ‘polder’ land (a polder is a low-lying tract of land enclosed by embankments known as dikes, that forms an artificial hydrological entity). The process of land reclamation was continued in the 19th and 20th century on an even larger scale. The largest lake reclamation scheme of the 19th century was that of the Haarlemmermeer (nowadays host to Schiphol international airport) in 1852, with a size of well over 18,000 hectares. Land reclamation in the 20th century was concentrated in the Lake IJssel area (with four polders with sizes of 20,000, 43,000, 48,000 and 54,000 hectares) . This lake was formed in the 1930’s after the construction of the Closure dam (Afsluitdijk). The dam was build in response to a major flood in 1916 in the area of the former Zuiderzee. Another serious storm surge in 1953 triggered the construction of the Delta works. The project included the closure of all sea inlets, except for the Rotterdam Waterway (entrance to the Port of Rotterdam) and the Western Scheldt (entrance to the Port of Antwerp). The Delta works together considerably shortened the total length of the coastline and thus the length of the potentially vulnerable coastal defenses. The plan for closure of the Eastern Scheldt, the largest sea inlet of all, was finally abandoned. In stead, after a societal debate, a storm surge barrier was build to maintain the Eastern Scheldt’s abundant marine flora and fauna, its rich tidal salt marshes and shellfish fisheries. The debate on the Eastern Scheldt was a landmark in the Dutch history of delta development. For the first time the need for safety against flooding was reconciled with environmental concerns.
  43. 43. This chapter will focus on extension and revitalization of infrastructure. It will discuss how infrastructure is being developed to enable delta life. It will be discussed how development of infrastructure may help to deal with the ever increasing pressure on available space in deltas and how it may help to secure future water supplies. Other important drivers for the development of infrastructure are the sea-ward extension of ports and the growing interest for the generation of renewable (hydro) energy. Environmental concerns play an important role in the design and construction of infrastructure. In fact these concerns have given rise to a shift in paradigm from building against nature to ‘Building with Nature’. There is also a trend towards more robust infrastructure in response to a growing risk aversion in societies. Another observation is that a lot of infrastructure in deltas is already present for decades or centuries. Rehabilitation of this infrastructure will be a tall order for the (near) future. Technological development may open new opportunities to enhance the functionality of infrastructural solutions. Technological development may also help to extend the life time of infrastructure and/or to develop more cost-effective designs and construction 43 methods of infrastructure. The perspectives of technological development are discussed at the end of this chapter. 3.2 Infrastructure to support economic development Dealing with pressure on available space Population growth and economic development lead to an ever increasing pressure on the available space in deltas. Basically there are two options to deal with this pressure: enlarge the available space or combine different functions of the available space. The first option: land reclamation was and is a proven way to deal with this pressure: However, the increasing pressure on the available space also drives a growing interest in the second option: the multifunctional use of infrastructure. Land reclamation The Netherlands has a century old tradition in land reclamation. Several 1000 km2 of land have been reclaimed from the 17th till the middle of the 20th century. The final polder that was reclaimed was Zuidelijk Flevoland in 1968 in the Lake IJssel area. The plans to reclaim one more polder in the Lake IJssel area (the so-called Markerwaard) were abandoned because of budgetary and
  44. 44. Extension and revitalization of infrastructure environmental reasons. Although the actual land reclamation came to a halt, the concept of land reclamation kept its attraction. In the last few decades various plans for land reclamation were developed, including an extension of the coast in between Hoek van Holland and The Hague (Plan Waterman) and an island in the North Sea to host a new airport, etc. None of these ideas, however, have yet been implemented. Most recently the new Delta Committee proposed a seaward extension of the coastline with about 1 km to promote coastal development more or less as a ‘by-product’ of improving the protection against coastal flooding. While land reclamation ideas in the Netherlands did not go beyond the drawing- board, land reclamation worldwide was a thriving business. The last decade Land reclamation shows a number of prestigious land reclamation projects being completed. These include the airport development in Hong Kong and the island resorts is a well-proven developments along the coast of Dubai. way to deal with Land reclamation has grown into a popular strategy in cases where the 44 pressure on the available space is high. The land reclamation examples of increasing pressure Hong Kong and Dubai are large scale and technologically advanced. Their implementation required large investments too. There are, however, also on space other ways of reclaiming land. In the delta of the Ganges / Brahmaputra in Bangladesh natural processes of river morphology are used to reclaim land on a local scale. The high dynamics of the rivers support a relatively cheap way of land reclamation. It compensates, however, only partly of the loss of land due to erosion. Multifunctional use of infrastructure. A promising way to respond to the increasing pressure on space is through Revitalization of multifunctional use of infrastructure. Revitalization of infrastructure opens new opportunities for multifunctional use. Examples to be discussed later in this infrastructure chapter include the transition of conventional embankments into super levees in Japan and the rehabilitation of the Closure dam of Lake in The Netherlands. opens opportunities Multifunctional use of infrastructure may be especially promising for flood for multifunctional protection works. Linking flood protection to other development issues such as urban (re)development or nature development may be an attractive way use to combine more immediate benefits of e.g. urban development with the long term benefits of flood protection. As such it may contribute to secure the necessary funds for improvement or maintenance of flood protection works.
  45. 45. Securing future water supplies Due to climate change prolonged and more frequent periods of drought are expected. At the same time water demands in deltas are increasing because of population growth and economic development. As a consequence water shortages will grow in magnitude and frequency, unless land and water use will be adapted or future water supplies will be improved either by storage or transfer. In many countries shortage of fresh water is viewed as one of the most serious challenges in water resources management. Even in a country such as the Shortages of fresh Netherlands, with generally an abundance of water, droughts occasionally occur. Due to climate change water shortages are expected to become more water are a major likely and counter measures are being considered. In fact the Delta committee has proposed to raise the target water level of Lake IJssel with some 1.5 m to concern in delta increase the amount of water being stored. The water from this lake provides a source of water supply to other parts of the country in periods of drought. development The expected increase in water shortages is a major trigger for adaptation worldwide to climate change. However in some countries such as Spain, the drought 45 problems are so acute that emergency measures are taken. Projects for improving the water supply may offer opportunities to realize other objectives as well. An example of such multipurpose development is the development of Marina Bay in Singapore, addressing flood protection, water supply and recreation. Box 3.2 Water shortages and adaptation to climate change (example from Spain) The drought problem in Spain is treated rather separately from the adaptation to climate change, despite the obvious and recognized link between the two. In general, drought is regarded as an emergency issue and many ad-hoc actions are taken. This happens often on a short time scale, which does not necessarily fit with the long-term adaptation to climate change. Many activities aim at solving particular bottlenecks caused by drought, especially in the irrigated agriculture. Examples of such measures are the implementation of interbasin transfers, a much disputed issue in Spain, as well as the continuous inauguration of desalination plants, especially close to the major coastal cities such as Barcelona. These kind of drought-driven activities are sometimes included in plans for adaptation to climate change, but tend to be implemented independent as a kind of ‘no-regret’ measures.